Functionalized Poly(N-isopropylacrylamide)-Based Microgels in Tumor Targeting and Drug Delivery.

Over the past several decades, the development of engineered small particles as targeted and drug delivery systems (TDDS) has received great attention thanks to the possibility to overcome the limitations of classical cancer chemotherapy, including targeting incapability, nonspecific action and, consequently, systemic toxicity. Thus, this research aims at using a novel design of Poly(N-isopropylacrylamide) p(NIPAM)-based microgels to specifically target cancer cells and avoid the healthy ones, which is expected to decrease or eliminate the side effects of chemotherapeutic drugs. Smart NIPAM-based microgels were functionalized with acrylic acid and coupled to folic acid (FA), targeting the folate receptors overexpressed by cancer cells and to the chemotherapeutic drug doxorubicin (Dox). The successful conjugation of FA and Dox was demonstrated by dynamic light scattering (DLS), Fourier-transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), UV-VIS analysis, and differential scanning calorimetry (DSC). Furthermore, viability assay performed on cancer and healthy breast cells, suggested the microgels' biocompatibility and the cytotoxic effect of the conjugated drug. On the other hand, the specific tumor targeting of synthetized microgels was demonstrated by a co-cultured (healthy and cancer cells) assay monitored using confocal microscopy and flow cytometry. Results suggest successful targeting of cancer cells and drug release. These data support the use of pNIPAM-based microgels as good candidates as TDDS.

Controlled release of microencapsulated docosahexaenoic acid (DHA) by spray-drying processing.

The omega-3-fatty acid, docosahexaenoic acid (DHA) 22:6 n-3, is an important food component for the visual and brain development of infants. In this study two approaches have been explored for the encapsulation of DHA in the pH dependant polymer hydroxyl-propyl-methyl-cellulose-acetate-succinate (HPMCAS). In the first approach Direct Spray Drying (DSD) was implemented for the microencapsulation of DHA/HPMCAS organic solutions, whilst in the second approach solid lipid nanoparticle (SLN) dispersions of DHA, were first produced by high-pressure homogenization, prior to being spray dried in HPMCAS aqueous solutions. The DSD approach resulted in significantly higher quantities of DHA being encapsulated, at 2.09 g/100 g compared to 0.60 g/100 g in the spray-dried SLNs. The DHA stability increased with the direct spray-drying approach. Release studies of DHA in the direct sprayed dried samples revealed a lag time for 2 h in acidic media followed by rapid release in phosphate buffer (pH 6.8).

Formation of a Bile Salt-Drug Hydrogel to Predict Human Intestinal Absorption.

The unique character of bile salts to self-assemble into hydrogels in the presence of halide salts was exploited in this work to facilitate the prediction of human intestinal absorption (%HIA) for a set of 25 compounds. This was achieved by firstly incorporating each compound separately within the process of gel formation to create a series of gel-drug membranes. Scanning electron microscopy analysis of the freeze-dried samples of the blank bile salt hydrogels and drug-loaded bile salt hydrogels indicated a unique microstructure made of a network of intertwined fibrils. Drug-loaded sodium deoxycholate hydrogels were then utilized as the donor phase to study permeability using flow-through and static diffusion cells. The resulting values of the release-permeability coefficient (Kp) were then analyzed, along with other molecular descriptors, for the %HIA using multiple linear regression. Overall, when comparing predicted values (using the systems presented in this study) with known literature values, it can be seen that both methods (i.e., using static and flow-through cells) had good predictability with R2PRED values of 79.8% and 79.7%, respectively. This study therefore proposes a novel, accurate, and precise way to predict HIA for compounds of pharmaceutical interest using a simple in vitro permeation system. It is important to develop alternatives to the current methods used in prediction of HIA, which are expensive and time-consuming or include the use of animals. Therefore, the proposed method in this study being economic and time-saving provides superiority over these current methods and suggests the possibility of its use as an alternate to such methods for prediction of HIA.

The development of a novel smart material based on colloidal microgels and cotton.

Colloidal microgels are often described as "smart" due to their ability to undergo quite dramatic conformational changes in response to a change in their environmental conditions (e.g. temperature, pH). A range of novel smart materials were developed by the incorporation of colloidal microgels into cotton fabric. A series of microgels have been prepared by a surfactant free emulsion polymerization based on N-isopropylacrylamide (NIPAM) monomer. Poly(NIPAM) is a thermosensitive polymer which undergoes a conformational transition close to the human skin temperature. Poly(NIPAM) was co-polymerized acrylic acid (AA), to prepare pH/temperature-sensitive microgels. Microgel particles were characterized by scanning electron microscopy (SEM), attenuated total reflectance fourier transform infrared (ATR-FTIR) spectroscopy, and dynamic light scattering (DLS). This research aims at coupling microgel particles onto cotton fibers and comparing between different attachment techniques. The coupling reactions between microgels and cotton cellulose are only feasible if they both have appropriate functionalities. For microgels, this was achieved by using different initiators which introduce different functional groups on the particle surface and different surface charges. Cotton samples were successfully modified by carboxymethylation, periodate oxidation, grafting of 1,2,3,4-butanetetracarboxylic acid, and chloroacetylation in order to target possible reactions with the terminal functional groups of the microgel particles. Microgels were attached to the cotton fabrics using different methods and the bonds formed were determined by ATR-FTIR spectroscopy and SEM. The reaction yields were quantified gravimetrically and the maximum weight increase of cotton samples due to the attached microgels was around 24% (w/w).

A quality by design (QbD) twin-Screw extrusion wet granulation approach for processing water insoluble drugs.

In this study, a Quality by Design (QbD) approach was used to identify the effect of formulation parameters in a twin screw wet extrusion granulation process for the manufacturing of ibuprofen (IBU) granules with increased dissolution rates. A fractional factorial Design of Experiment (DoE) was used to investigate the effect of the excipient composition, binder amount and liquid to solid (L/S) ratio (independent variables) on drug dissolution rates, median particle size diameter and specific surface area (dependent variables). The intra-granular addition of the binder in inorganic/polymer blends processed with ethanol as granulating liquids facilitated the formation of granules at various particle sizes. DoE regression analysis showed that all formulation parameters affect the dependent variables significantly. The enhanced dissolution rates were attributed not only to the IBU particle size reduction and adsorption in the porous inorganic network but also to the high specific surface area of the produced granules. Dynamic vapour sorption showed increased water absorption for granules with small particle size distribution and high specific surface area.

Solid-state flurbiprofen and methyl-ß-cyclodextrin inclusion complexes prepared using a single-step, organic solvent-free supercritical fluid process.

The aim of this study was to enhance the apparent solubility and dissolution properties of flurbiprofen through inclusion complexation with cyclodextrins. Especially, the efficacy of supercritical fluid technology as a preparative technique for the preparation of flurbiprofen-methyl-ß-cyclodextrin inclusion complexes was evaluated. The complexes were prepared by supercritical carbon dioxide processing and were evaluated by solubility, differential scanning calorimetry, X-ray powder diffraction, scanning electron microscopy, practical yield, drug content estimation and in vitro dissolution studies. Computational molecular docking studies were conducted to study the possibility of molecular arrangement of inclusion complexes between flurbiprofen and methyl-ß-cyclodextrin. The studies support the formation of stable molecular inclusion complexes between the drug and cyclodextrin in a 1:1 stoichiometry. In vitro dissolution studies showed that the dissolution properties of flurbiprofen were significantly enhanced by the binary mixtures prepared by supercritical carbon dioxide processing. The amount of flurbiprofen dissolved into solution alone was very low with 1.11±0.09% dissolving at the end of 60min, while the binary mixtures processed by supercritical carbon dioxide at 45°C and 200bar released 99.39±2.34% of the drug at the end of 30min. All the binary mixtures processed by supercritical carbon dioxide at 45°C exhibited a drug release of more than 80% within the first 10min irrespective of the pressure employed. The study demonstrated the single step, organic solvent-free supercritical carbon dioxide process as a promising approach for the preparation of inclusion complexes between flurbiprofen and methyl-ß-cyclodextrin in solid-state.

Monitoring real time polymorphic transformation of sulfanilamide by diffuse reflectance visible spectroscopy.

This study investigated the development of a novel approach to surface characterization of drug polymorphism and the extension of the capabilities of this method to perform 'real time' in situ measurements. This was achieved using diffuse reflectance visible (DRV) spectroscopy and dye deposition, using the pH sensitive dye, thymol blue (TB). Two polymorphs, SFN-ß and SFN-γ, of the drug substance sulfanilamide (SFN) were examined. The interaction of adsorbed dye with polymorphs showed different behavior, and thus reported different DRV spectra. Consideration of the acid/base properties of the morphological forms of the drug molecule provided a rationalization of the mechanism of differential coloration by indicator dyes. The kinetics of the polymorphic transformation of SFN polymorphs was monitored using treatment with TB dye and DRV spectroscopy. The thermally-induced transformation fitted a first-order solid-state kinetic model (R2=0.992), giving a rate constant of 2.43×10-2 s-1.

Continuous twin-screw granulation for enhancing the dissolution of poorly water soluble drug.

The article describes the application of a twin-screw granulation process to enhance the dissolution rate of the poorly water soluble drug, ibuprofen (IBU). A quality-by-design (QbD) approach was used to manufacture IBU loaded granules via hot-melt extrusion (HME) processing. For the purpose of the study, a design of experiment (DoE) was implemented to assess the effect of the formulation compositions and the processing parameters. This novel approach allowed the use of, polymer/inorganic excipients such as hydroxypropyl methylcellulose (HPMC) and magnesium aluminometasilicate (Neusilin(®)-MAS) with polyethylene glycol 2000 (PEG) as the binder without requiring a further drying step. IBU loaded batches were processed using a twin screw extruder to investigate the effect of MAS/polymer ratio, PEG amount (binder) and liquid to solid (L/S) ratios on the dissolution rates, mean particle size and the loss on drying (LoD) of the extruded granules. The DoE analysis showed that the defined independent variables of the twin screw granulation process have a complex effect on the measured outcomes. The solid state analysis showed the existence of partially amorphous IBU state which had a significant effect on the dissolution enhancement in acidic media. Furthermore, the analysis obtained from the surface mapping by Raman proved the homogenous distribution of the IBU in the extruded granulation formulations.

Implementation of transmission NIR as a PAT tool for monitoring drug transformation during HME processing.

The aim of the work reported herein was to implement process analytical technology (PAT) tools during hot melt extrusion (HME) in order to obtain a better understanding of the relationship between HME processing parameters and the extruded formulations. For the first time two in-line NIR probes (transmission and reflectance) have been coupled with HME to monitor the extrusion of the water insoluble drug indomethacin (IND) in the presence of Soluplus (SOL) or Kollidon VA64 hydrophilic polymers. In-line extrusion monitoring of sheets, produced via a specially designed die, was conducted at various drug/polymer ratios and processing parameters. Characterisation of the extruded transparent sheets was also undertaken by using DSC, XRPD and Raman mapping. Analysis of the experimental findings revealed the production of molecular solutions where IND is homogeneously blended (ascertained by Raman mapping) in the polymer matrices, as it acts as a plasticizer for both hydrophilic polymers. PCA analysis of the recorded NIR signals showed that the screw speed used in HME affects the recorded spectra but not the homogeneity of the embedded drug in the polymer sheets. The IND/VA64 and IND/SOL extruded sheets displayed rapid dissolution rates with 80% and 30% of the IND being released, respectively within the first 20min.

Commercial 'ready-to-feed' infant foods in the UK: macro-nutrient content and composition.

Quantitative analyses of the macronutrient content of eight popular commercial 'ready-to-feed' baby meals for 6-9-month old infants in the UK market have been undertaken in order to ascertain their nutritional suitability in relation to the total daily dietary intake as well as nutritional profiling of the products. The chemical analyses conducted included Kjeldhal for protein, acid hydrolysis and extraction for fat, phenol sulphuric acid for carbohydrate and Association of Official Analytical Chemists 985.29 for fibre. The only difference found between different varieties (meat- and vegetable-based) was with respect to the protein content (P=0.04) per 100 g of food. The experimentally determined concentrations of macronutrients (g/100 kcal) were compared with the declared values provided by the manufacturers on the product labels and, despite some variations, the values obtained comply with regulatory requirements (Commission Directive 2006/125/EC). The total daily intake of fat (27.0 g per day) - based on the menu composed from commercial complementary food - is suggested to exceed the daily recommended values for fat (31%), if the intake of snacks and desserts are incorporated. These findings imply that the formulation of recipes, based on a standard commercial menu, is an important consideration in relation to the nutritional quality of the diet of infants.

Prediction of polymorphic transformations of paracetamol in solid dispersions.

A novel approach employing variable-temperature X-ray powder diffraction (VTXRPD) was used to exploit its suitability as an off-line predictive tool to study the polymorphic transformations of paracetamol (PMOL) in melt-extruded hydrophilic polymer matrices. Physical mixtures (PMs) and extruded formulations of PMOL with either polyvinyl caprolactam graft copolymer (Soluplus®) or vinylpyrrolidone-vinyl acetate copolymer (Kollidon®) in the solid state were characterized by using differential scanning calorimetry, hot-stage microscopy, and scanning electron microscopy. The experimental findings from VTXRPD showed that the stable Form I (monoclinic) of PMOL transformed to the metastable polymorph Form II (orthorhombic) at temperatures varying from 112°C to 120°C, in both the PMs and extrudates suggesting an effect of both temperature and identity of the polymers. The findings obtained from VTXRD analysis for both the PMs and the extruded formulations were confirmed by in-line near-infrared (NIR) monitoring during the extrusion processing. In the NIR study, PMOL underwent the same pattern of polymorphic transformations as those detected using VTXPRD. The results of this study suggest that VTXRPD can be used to predict the polymorphic transformation of drugs in polymer matrices during extrusion processing and provides a better understanding of extrusion processing parameters.

An in-vivo and in-vitro taste masking evaluation of bitter melt-extruded drugs.

OBJECTIVES: The purpose of this study was to investigate the potential of hot-melt extrusion (HME) for masking the taste of bitter active pharmaceutical ingredients (APIs) when incorporated into different polymer formulations. METHODS: Extrudates were produced by HME using two water soluble cationic model drugs (cetirizine HCl and verapamil HCl) processed with various grades of anionic polymers (Eudragit L100 and Eudragit L100-55 (Acryl EZE)). The process was optimised by using a single screw extruder to produce extruadates with the desirable characteristics. KEY FINDINGS: In-vivo results obtained from a panel of six healthy human volunteers demonstrated that the HME extruded formulations improved the taste significantly compared with that of the pure APIs. In addition, an in-vitro evaluation carried out by an Astree e-tongue equipped with seven specific sensors demonstrated significant taste improvement of the extrudates compared with placebo polymers and the pure APIs. Furthermore, the extrudates characterised by SEM, X-ray and differential scanning calorimetry studies showed the existence of molecularly dispersed APIs while in-vitro dissolution showed fast release for all drug substances. CONCLUSIONS: HME can effectively be used to mask the taste of bitter APIs by enhancing drug-polymer interactions.

A review on the taste masking of bitter APIs: hot-melt extrusion (HME) evaluation.

The majority of active pharmaceutical ingredients (APIs) found in oral dosage forms have a bitter taste. Masking the unpleasant taste of bitter, APIs is a major challenge in the development of such oral dosage forms. Taste assessment is an important quality-control parameter for evaluating taste-masked formulations of any new molecular entity. Hot-melt extrusion (HME) techniques, have very recently, been accepted from an industrial compliance viewpoint in relation to both manufacturing operations and development of pharmaceuticals. HME achieves taste masking of bitter APIs via various mechanisms such as the formation of solid dispersions and inter-molecular interactions and this has led to its wide-spread use in pharmaceutical formulation research. In this article, the uses of various taste evaluation methods and HME as continuous processing techniques for taste masking of bitter APIs used for the oral delivery of drugs are reviewed.

Drug-polymer intermolecular interactions in hot-melt extruded solid dispersions.

The purpose of the study was to investigate and identify the interactions within solid dispersions of cationic drugs and anionic polymers processed by hot-melt extrusion (HME) technique. Propranolol HCl (PRP) and diphenhydramine HCl (DPD) were used as model cationic active substances while pH sensitive anionic methacrylic acid based methyl methacrylate copolymers Eudragit L100 (L100) and ethyl acrylate copolymer Eudragit L100-55 (Acryl EZE) (L100-55) were used as polymeric carriers. The extrudates were further characterised using various physicochemical characterisation techniques to determine the morphology, the drug state within the polymer matrices and the type of drug-polymer interactions. Molecular modelling predicted the existence of two possible H-bonding types while the X-ray photon spectroscopy (XPS) advanced surface analysis of the extrudates revealed intermolecular ionic interactions between the API amino functional groups and the polymer carboxylic groups through the formation of hydrogen bonding. The magnitude of the intermolecular interactions varied according to the drug-polymer miscibility.

Simultaneous determination of riboflavin and pyridoxine by UHPLC/LC-MS in UK commercial infant meal food products.

An assay for the simultaneous quantitative determination of riboflavin and pyridoxine in eight different complementary infant meal products has been developed in order to (1) estimate the daily intake of these vitamins from commercial infant food consumption, and (2) ascertain their nutritional suitability relative to dietary guidelines for the 6-9 months age group. The method involves mild hydrolysis of the foods, an extraction of the supernatant by centrifugation followed by quantitative determination using ultra-high performance liquid chromatography. Separation of the two water soluble vitamins is achieved within one minute and the resultant sample is also LC-MS compatible. Despite wide individual differences between brands (p=6.5e-12), no significant differences were observed in the level of pyridoxine between the meat and vegetable-based varieties (p=0.7) per 100g of commercial infant food. Riboflavin was not detected in any of the samples where the detection limit was below 0.07 µg/mL. In terms of the Reference Nutrient Intake (RNI) of pyridoxine for 6-9 months old infants, the complementary infant meal products analysed herein provided less than 15% of the RNI values with mean (SD) values of 12.87 (± 4.46)% and 13.88 (± 4.97)% for the meat- and vegetable-based recipes, respectively. The estimated total daily intake of riboflavin and pyridoxine from the consumption of commercial complementary food was found to be satisfactory and in accordance with the Dietary Reference Values (DRVs). The intake of both riboflavin and pyridoxine was estimated to be mainly derived from the consumption of formula milk which could be a cause of concern if the quality of an infant's milk diet is compromised by an inadequate or lack of supplemented milk intake. The results of this study suggest that the selected commercial complementary infant foods in the UK market may not contain the minimum levels of riboflavin and pyridoxine required for the labelling declaration of the micronutrient content of such products as recommended by Commission Directive 2006/125/EC.

Elemental content of commercial 'ready to-feed' poultry and fish based infant foods in the UK.

The study reported herein was conducted in order to establish the concentration of 20 essential and non-essential elements in a representative range of commercial infant foods in the UK targeted for infants aged between 6-12 months. The primary objective of this study was to examine the nutritive values and safety of such complementary infant foods on the UK market in relation to dietary and safety guidelines. Quantitative analyses were conducted on eight different products representing four popular brands (poultry and fish based) of ready to-feed infant foods currently on sale in the UK. Six essential elements, namely: calcium, iron, magnesium, potassium, sodium and zinc were determined by ICP-OES. The concentrations of six essential trace elements (selenium, molybdenum, cobalt, copper, chromium, manganese) and eight non-essential, potentially toxic, elements (arsenic, barium, nickel, cadmium, antimony, lead, mercury, aluminium) were determined by ICP-MS due to the higher sensitivity required. The total daily intakes of essential and trace elements from the consumption of such products were then estimated, based on the results of this study, and were referenced to the Recommended Nutrient Intake (RNI) values and safety guidelines for 6-9 months old children. Based on these comparisons the concentration of essential, except for potassium, and trace elements were found to be inadequate in meeting the RNI. In terms of the risk of exposure to toxicity, the concentration of toxic elements in ready to feed products analysed in this study, were not considered to be of concern. These results suggest that commercial complementary infant foods on the UK market may not contain minimum levels of minerals required for labelling declaration of micronutrient content (Commission Directive 2006/125/EC). This provides opportunities and scope for product optimisation to improve their nutritive value.

A review of hot-melt extrusion: process technology to pharmaceutical products.

Over the last three decades industrial adaptability has allowed hot-melt extrusion (HME) to gain wide acceptance and has already established its place in the broad spectrum of manufacturing operations and pharmaceutical research developments. HME has already been demonstrated as a robust, novel technique to make solid dispersions in order to provide time controlled, modified, extended, and targeted drug delivery resulting in improved bioavailability as well as taste masking of bitter active pharmaceutical ingredients (APIs). This paper reviews the innumerable benefits of HME, based on a holistic perspective of the equipment, processing technologies to the materials, novel formulation design and developments, and its varied applications in oral drug delivery systems.

Co-acquisition of hyperpolarised 13C and 15N NMR spectra.

Recent developments in dynamic nuclear polarisation now allow significant enhancements to be generated in the cryo solid state and transferred to the liquid state for detection at high resolution. We demonstrate that the Ardenkjaer-Larsen method can be extended by taking advantage of the properties of the trityl radicals used. It is possible to hyperpolarise 13C and 15N simultaneously in the solid state, and to maintain these hyperpolarisations through rapid dissolution into the liquid state. We demonstrate the almost simultaneous measurement of hyperpolarised 13C and hyperpolarised 15N NMR spectra. The prospects for further improvement of the method using contemporary technology are also discussed.

Applications of DNP-NMR for the measurement of heteronuclear T1 relaxation times.

Measurement of heteronuclear spin-lattice relaxation times is hampered by both low natural abundance and low detection sensitivity. Combined with typically long relaxation times, this results in extended acquisition times which often renders the experiment impractical. Recently a variant of dynamic nuclear polarisation has been demonstrated in which enhanced nuclear spin polarisation, generated in the cryo-solid state, is transferred to the liquid state for detection. Combining this approach with small flip angle pulse trains, similar to the FLASH-T(1) imaging sequence, allows the rapid determination of spin-lattice relaxation times. In this paper we explore this method and its application to the measurement of T(1) for both carbon-13 and nitrogen-15 at natural abundance. The effects of RF inhomogeneity and the influence of proton decoupling in the context of this experiment are also investigated.

Accuracy vs time dilemma on the prediction of NMR chemical shifts: a case study (chloropyrimidines).

The nuclear magnetic shieldings of two chloropyrimidine species have been predicted and analyzed by means of ab initio and DFT methods. The results have been compared with the experimental values and with those from other database-related approaches. These dataset-based techniques are found to be particularly valuable because of the accurate and instantaneous prediction of the 13C chemical shifts. On the other hand, only a few quantum chemistry based approaches were showed to be the most precise to predict 1H chemical shifts and to elucidate unequivocally the 1H NMR spectra of the regioisomeric mixture under study. Special emphasis was put on incorporating the solvent effect, implicitly, or explicitly. The influence of the level of theory and basis set in the predicted values has also been discussed.